From 0c755c927fa88e27c647f9c7c0062194ef290803 Mon Sep 17 00:00:00 2001
From: T-Dark <tdark.uuid@gmail.com>
Date: Tue, 19 Oct 2021 17:29:53 +0100
Subject: [PATCH] Fixed integer overflows. Why did I even write  in the first
 place?

---
 ablescript/src/brian.rs | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/ablescript/src/brian.rs b/ablescript/src/brian.rs
index 1a4bf120..1073f9b8 100644
--- a/ablescript/src/brian.rs
+++ b/ablescript/src/brian.rs
@@ -110,14 +110,14 @@ impl<'a, I: BootlegRead> Interpreter<'a, I> {
                 let val = self
                     .get_or_resize_tape_mut()
                     .ok_or(ProgramError::TapeSizeExceededLimit)?;
-                *val = val.checked_add(1).ok_or(ProgramError::IntegerOverflow)?;
+                *val = val.wrapping_add(1)
             }
 
             b'-' => {
                 let val = self
                     .get_or_resize_tape_mut()
                     .ok_or(ProgramError::TapeSizeExceededLimit)?;
-                *val = val.checked_sub(1).ok_or(ProgramError::IntegerUnderflow)?;
+                *val = val.wrapping_sub(1)
             }
 
             b'.' => {
@@ -282,8 +282,6 @@ pub enum IoStatus {
 /// An error that occurred while the interpreter was advancing
 pub enum ProgramError {
     DataPointerUnderflow,
-    IntegerOverflow,
-    IntegerUnderflow,
     InputReadError,
     UnmatchedOpeningBracket,
     UnmatchedClosingBracket,
@@ -297,8 +295,6 @@ impl Display for ProgramError {
             "{}",
             match self {
                 ProgramError::DataPointerUnderflow => "data pointer underflow",
-                ProgramError::IntegerOverflow => "integer overflow",
-                ProgramError::IntegerUnderflow => "integer underflow",
                 ProgramError::InputReadError => "input read error",
                 ProgramError::UnmatchedOpeningBracket => "unmatched `[`",
                 ProgramError::UnmatchedClosingBracket => "unmatched `]`",
@@ -442,4 +438,23 @@ mod tests {
             ))
         );
     }
+
+    #[test]
+    fn positive_integer_overflow() {
+        interpret_with_io(b"+[+]", std::io::empty(), std::io::sink()).unwrap();
+    }
+
+    #[test]
+    fn negative_integer_overflow() {
+        interpret_with_io(b"-", std::io::empty(), std::io::sink()).unwrap();
+    }
+
+    #[test]
+    fn in_the_past_this_used_to_crash_but_not_anymore() {
+        let mut interpreter = Interpreter::from_ascii(
+            b"[-]++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++>[-]++>[-]>[-]<<<[>>>+<<<-]>>>[<<[<+>>+<-]>[<+>-]>-]<<<------------>>++++++++++<<[->+>-[>+>>]>[+[-<+>]>+>>]<<<<<<]>>[-]>>>++++++++++<[->-[>+>>]>[+[-<+>]>+>>]<<<<<]>[-]>>[>++++++[-<++++++++>]<.<<+>+>[-]]<[<[->-<]++++++[->++++++++<]>.[-]]<<++++++[-<++++++++>]<.[-]<<[-<+>]<", 
+            std::io::empty()
+        );
+        interpreter.interpret_with_output(std::io::sink()).unwrap();
+    }
 }